The disclosed embodiments of the present invention relate to generating regulated output voltages, and more particularly, to a voltage converter having an auxiliary switch implemented therein and related voltage converting method thereof.
The DC/DC switching converter is an indispensable part of many power management systems. As all designs are put into an effort of size reduction, the voltage converter cannot stay out of that trend. Designers, therefore, are exploring the way to shrink the size in both on-chip and off-chip implementation. Of all the approaches, single-inductor multiple-output (SIMO) converters come to prevail. With only one single inductor to regulate more than one output voltage, the implementation can avoid problems that happen in conventional types of voltage converters, such as too many bulky power devices including inductors, capacitors, and control chips. Hence, the cost of mass-production is obviously much reduced. The SIMO design shows up as a most suitable and cost-effective solution in future development of DC-DC converter.
Many control schemes are proposed for SIMO converters based on buck topologies. For example, the control schemes may include a control scheme in a voltage mode, a control scheme in a current mode, a control scheme in a discontinuous conduction mode (DCM), and a control scheme in a pseudo continuous conduction mode (CCM). However, it is still a big challenge to DC-DC converter designers because an undesired phenomenon occurs when a load transient on any of converter outputs affects the voltage regulation of other converter outputs. From the efficiency's point of view, the control scheme in CCM is more attractive, and some CCM-based solutions for the SIMO converters have been proposed. The CCM-based solution, however, always encounters cross regulation between the different regulated output voltages of the SIMO converter.
The drawbacks of the conventional techniques, therefore, urge the development of a new control method for SIMO converters.